The present invention relates to a high-voltage lead-through for introducing a high voltage into a vacuum, particularly for corpuscular-ray apparatus, consisting of a high-voltage electrode, an insulator surrounding the high-voltage electrode, and an outer electrode at a lower potential which surrounds the insulator. Corpuscular-ray apparatus includes, as is known, electron and ion microscopes as well as electron beam apparatus.
In electron beam apparatus the cathode has a high negative potential which must be sufficiently well insulated from the housing, which lies at ground potential. Because of the large potential difference, the development of the high-voltage lead-through and its insulator become of particular importance.
From West German Patent No. 763,347 it is already known to separate two electrodes by an insulator and, in order to provide assurance against external arcing, to develop the insulator in such a manner that the two ribs present on the ends of the insulator have a shell shape which is open towards the corresponding associated insulator end, into which shell shape the outer electrode parts which are under voltage extend.
From West German Patent No. 898 048 there is known a beam generator having two or more acceleration stages, in which the cathode is separated from the first acceleration electrode and the first acceleration electrode is separated from the second, etc. by in each case an insulator. Between every two insulators there is a voltage-conducting supporting ring which on its inside bears an accelerating electrode and on its outside a high-voltage connection for said electrode. The insulators are provided with a dish-shaped rib in order to lengthen the outer arcing path, the outer edge of said rib being widened in upward direction to form cylindrical insulator parts.